Reduced Shmt2 Expression Impairs Mitochondrial Folate Accumulation and Respiration, and Leads to Uracil Accumulation in Mouse Mitochondrial DNA.

Autor:	Fiddler JL; Division of Nutritional Sciences, Cornell University, Ithaca, NY, USA., Xiu Y; Division of Nutritional Sciences, Cornell University, Ithaca, NY, USA., Blum JE; Division of Nutritional Sciences, Cornell University, Ithaca, NY, USA., Lamarre SG; Department of Biology, University of Moncton, Moncton, New Brunswick, Canada., Phinney WN; Department of Medicine, University of Colorado, Aurora, CO, USA., Stabler SP; Department of Medicine, University of Colorado, Aurora, CO, USA., Brosnan ME; Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland, Canada., Brosnan JT; Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland, Canada., Thalacker-Mercer AE; Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA., Field MS; Division of Nutritional Sciences, Cornell University, Ithaca, NY, USA.
Jazyk:	angličtina
Zdroj:	The Journal of nutrition [J Nutr] 2021 Oct 01; Vol. 151 (10), pp. 2882-2893.
DOI:	10.1093/jn/nxab211
Abstrakt:	Background: Adequate cellular thymidylate (dTMP) pools are essential for preservation of nuclear and mitochondrial genome stability. Previous studies have indicated that disruption in nuclear dTMP synthesis leads to increased uracil misincorporation into DNA, affecting genome stability. To date, the effects of impaired mitochondrial dTMP synthesis in nontransformed tissues have been understudied. Objectives: This study aimed to determine the effects of decreased serine hydroxymethyltransferase 2 (Shmt2) expression and dietary folate deficiency on mitochondrial DNA (mtDNA) integrity and mitochondrial function in mouse tissues. Methods: Liver mtDNA content, and uracil content in liver mtDNA, were measured in Shmt2+/- and Shmt2+/+ mice weaned onto either a folate-sufficient control diet (2 mg/kg folic acid; C) or a modified diet lacking folic acid (0 mg/kg folic acid) for 7 wk. Shmt2+/- and Shmt2+/+ mouse embryonic fibroblast (MEF) cells were cultured in defined culture medium containing either 0 or 25 nM folate (6S-5-formyl-tetrahydrofolate, folinate) to assess proliferative capacity and mitochondrial function. Chi-square tests, linear mixed models, and 2-factor ANOVA with Tukey post hoc analyses were used to analyze data. Results: Shmt2 +/- mice exhibited a 48%-67% reduction in SHMT2 protein concentrations in tissues. Interestingly, Shmt2+/- mice consuming the folate-sufficient C diet exhibited a 25% reduction in total folate in liver mitochondria. There was also a >20-fold increase in uracil in liver mtDNA in Shmt2+/- mice consuming the C diet, and dietary folate deficiency also increased uracil content in mouse liver mtDNA from both Shmt2+/+ and Shmt2+/- mice. Furthermore, decreased Shmt2 expression in MEF cells reduced cell proliferation, mitochondrial membrane potential, and oxygen consumption rate. Conclusions: This study demonstrates that Shmt2 heterozygosity and dietary folate deficiency impair mitochondrial dTMP synthesis in mice, as evidenced by the increased uracil in mtDNA. In addition, Shmt2 heterozygosity impairs mitochondrial function in MEF cells. These findings suggest that elevated uracil in mtDNA may impair mitochondrial function. (© The Author(s) 2021. Published by Oxford University Press on behalf of the American Society for Nutrition.)
Databáze:	MEDLINE
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